a) Field of the Invention
The present invention relates to a split mechanism for a coaxial photographing device, and more particular to a split, assembly and disassembly mechanism between a photographing unit and a light projection unit of a photographing device used for a full-time surveillance.
b) Description of the Prior Art
A coaxial photographing device is used in a surveillance system, wherein an auxiliary light source is provided in a night projection to serve as a photographing device for a full-time surveillance, with an optic axis along which images are coming into the device same as an optic axis along which light is projecting.
Referring to FIG. 9, a photographing device 9 includes primarily a light projection module 92 which is coaxially attached with a photographing module 91 with a same optic axis S, wherein lens 910 is transfixed through a central through-hole 95 of the light projection module 92 to be attached coaxially. For the conventional photographing device 9, the photographing module 91 is coaxially attached with the light projection module 92 and is enclosed by a serially connected housing 90, with an end being connected to an electric wire 97 which provides an electronic driving device 93 with operating power and signal transmission. The electronic driving device 93 is connected to a lead wire 950, an end of which is linked to a pull terminal 921, with the light projection module 92 being provided with the operating power through an electric wire 920
An exterior of the light projection module 92 is protected by a lens 922, and the light projection module 92 is serial LED dices which are arranged on a surface of a circuit board 923 The circuit board 923 is also provided with a through-hole for transfixing the lens 910, and the photographing module 91 is provided at a rear end in an interior of the serially connected housing 90, with a front end of the photographing module 91 being coaxially assembled with the light projection module 92.
As the photographing device 9 is used full-time, images should be adjusted on-site before using. In addition, as the photographing device 9 is put up in high sky to look down on a ground, implementation personnel should climb high to adjust.
In order to adjust the photographing module 91 for acquiring the correct images, optic parameters should be adjusted through an adjustment key 96 according to an optic condition of the site. If the photographing device operates in daylight environment, then only a value of sensitivity or focus required for the images in the daylight environment can be acquired through the adjustment with the adjustment key 96. However, the adjustment value is not in compliance with a nighttime auxiliary light source, as in particular, invisible infrared is emitted by the light projection module 92 at the nighttime to prevent to visible light from affecting people, events and objects. Therefore, the image adjustment value of the photographing device 91 is based on the daylight condition, and when at the nighttime that only the infrared is emitted, the images will be distorted or blurred from various conditions due to difference in wavelength. On the other hands if the infrared is used as a calibration base for adjustment, then the photographing device can be applied in the daylight. Accordingly, in principle, the wavelength of the infrared should be used as the calibration base for the operation of the photographing module 91.
For the calibration with the infrared, the adjustment should be implemented at dark, and hence, the auxiliary light should be needed to maintain the operation, and the optic axis should be at least parallel to or project in a same direction to an area of photographing.
As the conventional design is an assembly of a single unit, when the adjustment key 96 of the photographing device 91 needs to be adjusted, the light projection module 92 should be disassembled, and the electric wire 920 should be unplugged from the pull terminal 921 therefore the light projection module 92 is separated but is also scattered. During this time, other extension wire will be used to transmit the power of the pull terminal to the light projection module 92 as illumination energy.
As the light projection module 92 is scattered after being disassembled, the optic axis should be held by another hand of an adjustment person or by a second person, allowing a light beam of the light projection module 92 to irradiate to the required photographing area, such that after that photographing area has been irradiated by the infrared, the optic parameters of the adjustment key 96 can be adjusted.
The conventional photographing device is provided with following shortcomings:                1. As the light projection module will be scattered after being disassembled by the high sky operation, it will result in a danger.        2. As two adjustment persons are usually required to operate at a same time, a manpower loading and a danger of high sky cooperation will be increased.        3. Upon reassembling after adjustment, a rim of the through-hole of the light projection module will hit the lens, which may allow the lens to be shifted or damaged.        4. If the exterior of the device is further protected by a protection lens, then an interior surface of the protection lens will reflect a scattered wave of the infrared to enter into the lens, thereby affecting the photographing condition of the lens.        5. When adjusting, as the auxiliary light is held by a bare hand, a swinging will be resulted. If the object to be photographed is there-dimensional, then reflection brilliance is at a left, right, upper or lower side of the object will be changed due to the swinging, allowing the adjustment work to be lengthy and repetitive, which is one of major obstacles in the adjustment operation. Therefore, the adjustment work will take a substantial percentage in installation cost.        